It's being described as scaremongering because it's scaremongering.
There are engineering solutions to the issues Woodward raises, in the same way if I or some of the other OLE engineers were to suggest, quite credibly, running at 250mph could cause the OLE to fail, it would, technically, be true, unless changes were made to increase contact wire cross section/weight, tightened mast spacing, and increased tensioning.
186mph running using the Mark 3b OLE on the ECML, particularly with two pantographs raised as per the Class 373 trainsets, would result, fairly quickly in a dewirement and almighty mess (in fact 125mph running with the Regional Eurostar sets was an issue and is still banned).
The same trains work almost flawlessly day in, day out, on HS1, because there's an engineering solution, which is a catenary built around heavier duty contact wire and higher tension. The engineering cost of the upgraded OLE is minimal in the grand scheme of things, fractions of pennies in the pound, engineering out any genuine issues with track, related to speed, is, I'm told, easily achievable and affordable, well accommodated within the budget and in comparison with tunnelling and structures costs, a staggeringly tiny cost.
I can still (just) remember the tales of doom, of derailed trains and dead bodies everywhere that ASLEF prophesied would happen with 125mph trains having only one member of staff in the driving cab. We hear all sorts from plenty of people who in theory can be trusted, but you need to question why they're saying what they're saying and if they're only telling half the story.